The present invention relates to a linear illuminant system which has good water resistance and good environmental resistance, which requires only a low power for operation, and which is especially appropriate for use in a scanning device. It also relates to a method for manufacturing the linear illuminant system with good productivity and at low cost. Furthermore, it relates to a scanning device comprising the linear illuminant system.
Conventional linear illuminant devices include neon tubes, fluorescent tubes and cold cathode tubes. These tubes require high voltages and such power as high as several tens of watts per meter, and also require lighting devices like an inverter, thus those tubes come costly. Where neon tubes and fluorescent tubes are used in a bent form, the advanced technique of skilled glassworkers is required, resulting in an increased cost. Furthermore, these tubes have problems in impact resistance and water resistance.
In order to solve problems described above, optical transmission tubes in the form of a flexible tube filled with a transparent core liquid or a flexible transparent polymer and strands of plastic optical fibers have been proposed. Each of these tubes and strands is designed such that light from a light source enters into the tube through one end thereof to emerge from a side surface area of the tube over a length of several tens of meters. Since this emerging area can be separated from the light source and is free of the risk of breakage, it can be used in water, outdoor, or even in an environment with the risk of explosion. The tubes and strands eliminate cumbersome working such as glass working. So, they are easily manufactured and processed, and are readily applied at necessary sites.
These optical transmission tubes are designed to provide light emergence over a length of several tens of meters. Since the light emergent efficiency at the side surface is low, a high power light source of about 50 to 250 W is required in order to provide a sufficient luminance. Even to provide light emergence over a short length such as several tens of centimeters, these optical transmission tubes require high power light sources just as neon tubes and fluorescent tubes.
One possible measure for increasing the luminance at the side surface area of an optical transmission tube is to corrugate the inner surface of a tubular cladding, and the other is to disperse scattering particles into a core. However, when these measures are taken, light emergence is provided from all over the side surface area of an optical transmission tube and not from a desired direction with a sufficient luminance.
It is an object of the present invention to provide a linear illuminant system requiring only a low power to produce side luminance with a high directivity, which can be manufactured with good productivity and is compact so that it may be installed at any desired place. Another object of the invention is to provide a scanning device comprising the linear illuminant system.
A further object of the invention is to provide a method for manufacturing the linear illuminant system with good productivity and at low cost.
A linear illuminant system of the present invention consists of a light emerging device composed of a transparent light transmission cylinder, a light source coupled to at least one end of the light emerging device, and at least one strip-shaped reflecting layer formed by printing along the length of the light transmission cylinder, wherein the light transmission cylinder receives light from the light source and emits it from the side surface area thereof.
The linear illuminant system of this invention has the strip-shaped reflecting layer formed along the length of the light transmission cylinder to reflect light passing through the light transmission cylinder. Reflected light forms linear light with high directivity and luminance to emerge from the side surface area opposite to the reflecting layer. Consequently, strong side luminance with sufficient brightness is obtained.
In a method for manufacturing the linear illuminant system of the present invention, the reflecting layer is formed on the side surface of the extruded light transmission cylinder by printing in line with the extrusion molding process of the light transmission cylinder.
In the method of the present invention, by introducing such in-line printing, the reflecting layer of the linear illuminant system can be easily and efficiently formed with good productivity.
A scanning device of the present invention comprises aforementioned linear illuminant.